Add rudimentary method to parse callback types
Put the main parsing before collecting type references

This is in preparation of a different approach to type references
collection that needs the TypeRegistry built during normal parsing.
Add a method to ConvertedType that gets its qualified name
Improve type reference collection using TypeRegistry

Now that normal parsing creates a TypeRegistry from all the defined
types it finds before starting dumb type reference collection,
we can use it to tell if a type reference is of a global type, or
a locally defined one, without any guesswork from the type name.
The previous "heuristic" method tried to guess this from the
format of the name, but it did not work in all cases.
Add some comments, and new mappings to static-mappings

Based on the generated undefined types list, add some new static
mappings, and some remarks about them, and the file itself.
Refactor out some constants to a Constants class